The human heart is a four chambered, muscular organ that provides blood circulation through the body during a cardiac cycle. The four main chambers include the right atria and right ventricle which supplies the pulmonary circulation, and the left atria and left ventricle which supplies oxygenated blood received from the lungs to the remaining body. To ensure that blood flows in one direction through the heart, atrioventricular valves (tricuspid and mitral valves) are present between the junctions of the atria and the ventricles, and semi-lunar valves (pulmonary valve and aortic valve) govern the exits of the ventricles leading to the lungs and the rest of the body. These valves contain leaflets or cusps that open and shut in response to blood pressure changes caused by the contraction and relaxation of the heart chambers. The leaflets move apart from each other to open and allow blood to flow downstream of the valve, and coapt to close and prevent backflow or regurgitation in an upstream manner.
Diseases associated with heart valves, such as those caused by damage or a defect, can include stenosis and valvular insufficiency or regurgitation. For example, valvular stenosis causes the valve to become narrowed and hardened which can prevent blood flow to a downstream heart chamber from occurring at the proper flow rate and may cause the heart to work harder to pump the blood through the diseased valve. Valvular insufficiency or regurgitation occurs when the valve does not close completely, allowing blood to flow backwards, thereby causing the heart to be less efficient. A diseased or damaged valve, which can be congenital, age-related, drug-induced, or in some instances, caused by infection, can result in an enlarged, thickened heart that loses elasticity and efficiency. Some symptoms of heart valve diseases can include weakness, shortness of breath, dizziness, fainting, palpitations, anemia and edema, and blood clots which can increase the likelihood of stroke or pulmonary embolism. Symptoms can often be severe enough to be debilitating and/or life threatening.
Heart valve prostheses have been developed for repair and replacement of diseased and/or damaged heart valves. Such valve prostheses can be percutaneously delivered and deployed at the site of the diseased heart valve through catheter-based systems. Such heart valve prostheses can be delivered while in a low-profile or compressed/contracted arrangement so that the valve prosthesis can be advanced through the patient's vasculature. Once positioned at the treatment site, the valve prosthesis can be expanded to engage tissue at the diseased heart valve region to, for instance, hold the valve prosthesis in position. While these valve prostheses offer minimally invasive methods for heart valve repair and/or replacement, challenges remain to providing effective, less invasive, smaller crossing profile prosthetic valve delivery systems, particularly for mitral valve replacement. For example, catheter delivery approaches and techniques for mitral valve replacement may utilized a transeptal approach. However, with the valve prosthesis retained within a capsule of the delivery system, challenges, such as capsule travel within the confined space of the left atrium may limit positioning of a heart valve prosthesis in the native mitral valve. Moreover, the capsule adds to the crossing profile of the catheter. Catheter crossing profile, especially for inter-atrial septum puncture, limit both the feasibility of heart valve prosthetic delivery as well as the size of the heart valve prosthesis. Alternatively, elimination of the capsule and radial contraction of the valve prosthesis by methods such as cinching reduces crossing profile of the catheter, but the exposed or uncovered valve prosthesis may damage native anatomy during delivery.
Further, in some patients, the valve prosthesis may not perform as desired following implantation. For example, the valve prosthesis may not 100% coapt to the wall of the native valve, resulting in paravalvular leakage (PVL). A sealing element or skirt may be disposed between the wall of the native valve and the valve prosthesis to limit PVL. However, inclusion of a sealing sleeve also adds to the crossing profile of the catheter.
Accordingly, there is a need for a system that minimizes the crossing profile of a catheter, provides sealing of a valve prosthesis to a native valve wall, and assists in atraumatic delivery of the valve prosthesis to the target site.